Insulator.



L. MOGARTHY.. INBULATOB.

APPLIUATIOI FILED FEB.'?.4, 1907.

922,313. y Patented May 18, y1909.

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ww'we: Zwwewarx www uw w17 l t l i l MM-f f UNITED 'STATES agritur orsrcn LOUIS MCCARTHY, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO THE MACALIlEN COMPANY,

OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

INsULA'roR.

Specication of Letters Patent.

Patented May is, 1909.

Application led February 14, 1907. Serial No. 357,266.

To all whom it may concern:

Be it known that I, LOUIS MC'CARTHY, citizen of the United States, residing at Boston, county of Suffolk, State of Massachusetts, have invented a certain new and useful Improvement in Insulators, of which the followlng is a specification, reference being had therein to the accompanying drawings.

Heretofore, insulators for many purposes, such for example as insulating jolnts for gas and electric fixtures for insulating turnbuckles, hangers for trolley wires used in the overconstruction of electric railways and insulators for many other purposes have been made with metallic members whose proximate ends are separated from each other by means of layers composed in whole or in part of sheet mica. Examples of such insulators may be seen by reference to various patents of the United States heretofore granted to me and especially to Letters Patent N o. 449,943, April 7, 1891 and No. 478,518, July 5, 1892. Such insulators have been finished 1n various ways, as for example by the application to the whole or a portion of the exterior of a covering of molded insulating material. It has been my experience that the power of this mica insulatlon to withstand the assage of an electric current is increased wlien the mass of la ers of mica composin the insulation is su jected to pressure. y belief is that this result is due to the fact that the pressure diminishes the interstices in the layered mass of insulation and lessens the amount of air and moisture which is contained in the insulatin mass. If the insulating mass be subjecte to a very high degree of ressure, I have found that its insulative qua 1ty is very considerably improved. Believing that the more perfect removal of all spaces containing air or moisture in the insulating mass, even although these s aces be ver minute would increase still furt er the insu ative quality of the mass, I have taken steps to this end and have in practice produced an insulator of much improved insulative quality.

In the production of my improved insulator, I take an insulator, the arts of which have been built 'u and mec anically combined and secured m the well known manner, and place it in a chamber from which the air is then exhausted by suitable exhaust mechanisn. The exhausting of the air takes out from the insulator a very substantial portion of the air and moisture which are contained in the crevices which are unavoidable in the mechanical construction thereof, as well as in the interstices which, although frequently very minute, are to be found in the insulation itself. When there is as reat a degree of vacuum formed as is possib e or practicable in the chamber containing the insulator, I admit into the chamber a mass of insulating compound or composition which is solid at the ordlnary tem eratures but which under 65 the influence of a igh degree of heat becomesl a very thin liquid. In practice I have employed a composition known to those skilled in the art by the name ofy Ohmlac which I believe to consist of Egyptian asphaltum and animal and mineral oils. In this hot and liquid state the thin liquid fills every crevice and interstice of the insulator and to further insure its penetrating every opening however minute, I reverse the exhaust mechanism and apply an air pressure to the hot liquid. In practice I have used 60 pounds to the square inch. When the insulator has been subj ected to this for a sufficient time to insure the thorough penetration of the liquid into every opening in th'e insulator, I open the connection between the receiver containing the insulator and the receptacle for the hot liquid and the ressure on the receiver operates to force al of the free liquid back lnto the receptacle, leaving only such liquid as is in the crevices or interstices or openings of the insulator and a thin film which adheres to the surfaces of the insulator. The insulator is then removed and the hot liquid insulation allowed to set and harden, after which the insulator may be finished in any of the well known ways, as for example by treatment with dry heat to further harden the material applied as above described or by appl ing to all or part of the surfaces or joints o the insulator an outer molded covering or in any other well known manner.

For convenience of illustration and explanation, I have in the accompanying drawings shown my invention as applied to two common forms of insulators-a pipe insulator and a trolley wire insulator.

My invention, which has for its object to provide an insulator of improved insulative (quality, will be fully understood from the escription herein contained taken in connection with the accompanying drawings,

I have pointed out and clearly defined the novel features of my invention in the claims at the close of this specification.

In the drawings,-Figure 1 is a vertical section of a pipe insulator. Fig. 2 is a similar view of a common form of bell insulator such as is used in electric railway work.

Referring to the drawings,` -A and B indicate metallic coupling members which in the form shown are screw threaded and which it is the province of the insulation to electrically insulate from each other. In Fig. 1 the end of the member A is flanged as shown at 2 and the proximate end 3 ofthe member B, which is originally cu -shaped, is, after the said part 2 hasbeen p aced therein with the proper intervening insulation 4 and 5, crimped in or turned over the said insulation and the said part 2. The insulation is preferabl subjected to as much compression as possi le and the clamping of the part 3 over 1t to secure the whole construction together operates to -maintain it in its compressed condition. As will be clear, however, a perfect fitting of the parts is mechanically7 impossible and in practice there are crevices which contain air and moisture between the insulation and the adjacent walls of the metallic coupling members, and also in the insulation itself. To remove the moisture and air from these openings, spaces and interstices I place the joint in a proper closed vessel or receptacle to which is connected an air pump or other suitable mechanism by which the air may be withdrawn from the said vessel and a substantial degree of vacuum produced. The removal of thc air takes with it a yvery large degree of the moisture. From a suitable chamber connected with the said receiver I introduce therein by opening a valve in the connection an insulating compound or composition which is solid at normal temperature and which in the presence of a hlgh de ree of heat becomes a very thin liquid. n the liquid condition, this mass is ermitted to pass into the receiver from Whic the air has een removed. It immediately permeates and penetrates every crevice and opening in the receiver isclosed, the air pump is then reversed and a suitable air pressure is alplied. This insures the'penetration of t e ot-li uid into the openings in the insulation and t e illing of every crevice and crack.

Thel connection between the chamber containin the insulator and the hot liquid receptae is then opened and the air pressure drives out all of the liquid from the chamber excepting only such as may adhere to the surface of the chamber, and such as is contained within the spaces and crevices and minute o enings wh1ch are in the insulator. The insu ator is then removed and may be iinished either in the presence of dry heat or by being covered in whole or in part with a molded covering or in any otherwell known manner.

What I claim is:

1. An insulator comprising metallic portions sparatedby laminated insulation and having the crevices and interstices of said laminated insulation free from air and moistureand filled with an insulating compound commerically known as ohmlac.

2. An insulator comprising metallic portions separated by lammated insulation and having the crevices and interstices of said laminated insulation free from air and moisture and filled with an insulating compound consisting of Egyptian asphaltum and animal oil and mineral oil commercially known as ohmlac, said insulating compound being characterized by the quality that it becomes a thin liquid when subjected to a high degree of heat and solidifies at normal atmos-` pheric temperature.

In testlmony whereof I affix my signature, in presence of two Witnesses.

, LOUIS MCCARTHY.

Witnesses WM. A. MAoLEoD, GEORGE-1P. DIKE. 

